Fiber optic transmission of sensitive information is now widely used by security-conscious government and military agencies because of the extremely low RF emission characteristics and resistance to tapping of fiber optics as compared to conventional copper connections. The conversion interface of the wired connections with the fiber optic system remains, however, a source of RF radiation which must be carefully controlled in order to assure adequate data security. Accordingly, organizations like the National Security Agency (NSA) require interface equipment to meet stringent RF emission standards, for instance the TEMPEST requirements.
In the past, the conventional approach to achieving very low levels of RF emmissions from a conversion interface has been one of containment, wherein the interface unit is totally enclosed to prevent RF radiation from escaping. This strategy has generally required that the front end and front access panels of the unit be sealed closed with a cover using RF gaskets. Thus, accessing the front panels of the interface circuitry has required that the cover be removed, resulting in undesirable RF emission while the unit is open. Furthermore, it is known to often happen that technicians fail to properly resecure the cover after front panel access, resulting in a loss of compliance with the desired standards, and a possible security compromise.